We take a look at technology in the aquaculture industry
Transcript
July | August 2014 Fish Farming Technology supplement The International magazine for the aquaculture feed industry International Aquafeed is published six times a year by Perendale Publishers Ltd of the United Kingdom. All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. Copyright 2014 Perendale Publishers Ltd.All rights reserved.No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058 INCORPORATING FISH FARMING TECHNOLOGY
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SUPPL EMEN T FISH FARMING TECHNOLOGY SUPP LEMENT Technology round up Stock protection Biomass control
O ver the last three years Hvalpsund has been involved in developing a revolutionary new stock protection system for Huon Aquaculture in Tasmania,Australia. Huon is a vertically integrated company, farming, processing and selling premium quality Atlantic salmon and rainbow trout products to domestic and international markets. As the only 100 percent Australian-owned salmon farming business in Australia, Huon employs over 480 staff and will produce around 15,000T of salmon and trout this year Huon owners, Peter and Frances Bender approached the Danish net manufacturer at Aquanor back in 2011, as they wanted to find partners to develop a new system to keep out seals and birds. Seals, in particular, prove a real headache in Tasmania, costing the company in the region of Aus$12-18 million per year. These costs come from direct losses caused by seals getting into the pen and killing the fish, as well as the impact of stress induced in the salmon by the seal attacks. Moreover, the risk of attacks means that the company needs to have dedicated teams of staff patrolling the marine farm leases day and night in an attempt to keep seals away from the pens and off the collars, as well as employing extra personnel to release any seals that get into the pens. Not only is killing seals strictly forbidden in Australia, but any death of a seal would also be very negatively perceived by the public. As a result, the company recognised that huge savings could be achieved by develop- ing a better way to fence off the seals from attacking fish and to improve safety for per- sonnel working on the farms. They had tried various net materials in the past, but with poor effect and now they wanted to go into a completely new direction that would improve safety for both fish and personnel. Hvalpsund suggested a trial using the ultra- strong and light Dyneema fibre for the nets a material they have plenty of experience of working with. Some of the early tests showed that it was not enough just to spec up the twine size, however finding the right combination of twine size and strength and combining both knotted and raschel knotless materials eventu- ally proved to be the key. As no other salmon farm in the world had ever required nets with such high strength, the project was truly revolutionary. By trialing different kinds of nets and pens Hvalpsund worked with Huon to determine the best system to keep seals and birds away from the fish and feed. Key to the design The key to the design is the use of an extra-wide, triple-collar stanchion that has specialised outer sockets to accommodate a seal fence post and bird net pole. The seal fence post allows an outer seal fence net surrounding the entire pen to rise 2.8 metres above the surface of the water. The idea of the extra wide pen is to main- tain a good degree of separation between the outer seal fence and the inner containment net. The outer seal fence net is made using 125mm black knotted Dyneema with a breaking strength of over 1200kg. It is also fitted with strong Dyneema vertical ropes from which the sinker ring is suspended by hanging the heavy sinker rings directly from the seal net it is kept as tight as possible all the time, which makes it more difficult for the seals to push the net or bite it. The inner containment net is made with light yet strong Dyneema which ensures good water flow through the pen and reduces fouling. As the outer seal net is permanently in place, the pen is kept as a safe work environ- ment where daily operations or net changes can be done without the risk of seals attacking stock or personnel. The wide clearance between the outer seal net and inner containment net means that the nets can be cleaned using in situ net wash- ers. The system also includes an ultra-light bird net that is suspended high above the surface by light, flexible poles. The specially-designed, injection-moulded HDPE stanchions can be fitted with walkway plates either between the inner collars or both collars. This design provides a safe work- ing space for doing daily operations on the pens, even in bad weather. The advantage of using a pen made with only HDPE is that it requires far less maintenance than pens with steel components. Huon is also now investi- gating the potential for the pen stanchions to be constructed with injection-moulded nylon which, if successful, will make the stanchion even stronger. The original trial has proved to be so suc- cessful that Huon has now decided to replace all their existing pens with the new system. However, the real benefit will not come into play until all the pens at the site are replaced as long as some of the pens with the old design are still in use the seals will target these. Hvalpsund Net is a family-owned and -run company based in Denmark with 20 employees in the headquarter, warehouse in Hvalpusnd. The company has its own pro- duction in Poland with 80 workers mainly assembling aquaculture nets. Main export areas are Faroe Islands, Iceland, Scotland, Spain, Malta, Malaysia and Tasmania. The focus at Hvalpsund Net is to make cages, nets and mooring system for offshore aquaculture sites. Stock protection: pushing the boundaries 02 | INTERNATIONAL AQUAFEED | Fish farming Technology FISH FARMING TECHNOLOGY
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IT GOES WITHOUT SAYING THAT YOUR BUSINESS STANDS WITH THE RIGHT INFORMATION BUT CAN FALL BADLY WITH INACCURATE WEIGHTS AND FISH NUMBERS. T hats a quotation by Steve Bracken of Marine Harvest Scotland which Hermann Kristjansson, CEO and co- founder of Vaki Aquaculture Systems Ltd, began his talk at Aquaculture UK 2014 recently in Aviemore, Scotland. Mr Kristjansson presented his experience and views on Biomass Control, which has been listed as one of the challenges in Scottish salmon farming and in salmon farming in general. Started Vaki when he graduated from the University of Iceland in 1986. Since then he has concentrated on developing fish counters and size estimators for fish farming. Three years ago, Marine Harvest, Salmar and Leroy formed a pro- ject with SINTEF in Norway, the largest independent research institute in Scandinavia, to improve the Biomass Control in salmon farming. The total budget of the project, called EXACTUS, was UK3 mil- lion, which confirms the importance of Biomass Control as seen by these three companies. A recent study conducted by PHD student Arnfinn Aunsmo from Aas University in Norway shows that the error in number of fish and average weight harvested from individual cages is high. The error reported on average weights is more that +/- five percent in 30 percent of the cases. There is evidence that show similar figures in Scotland even though aggregate results often show that people are harvesting approximately what they expect from a complete site. Serious problem Biomass Control is considered a serious problem/challenge in fish farming. Now, why is it a challenge? Everybody can agree that poor bio- mass control can lead to unnecessary negative environmental impact. But what Mr Kristjansson addressed is the challenge of getting the most out of production: How to achieve maximum yield with minimum cost. Very few people are concerned with the profitability of salmon farming today given the current price of salmon. But over the past 28 years that Mr Kristjansson has been in the industry, prices have not been very stable and he thinks it would be considered irresponsible not to prepare for some price fluctuation in the near to medium future. In order to achieve maximum yield at minimum cost, higher indus- trialisation of the farming process is required. Tight monitoring and control of factors, that can be controlled, is needed. We need to collect as much data as possible and go into as much detail as possible monitoring exact weights and numbers all the way from hatching to harvest, he explained. Mr Kristjanssons experience is that
